pb6.5调用systemparamtersinfo设置桌面背景报错：
API声明：
function long systemparametersinfo (long uaction , long  uparam, ref any lpvparam, long  fuwinini )  library "user32.dll" alias for "systemparametersinfoa"

代码及报错：
constant long SPI_SETDESKWALLPAPER = 20
constant long SPIF_UPDATEINIFILE = 1
constant long SPIF_SENDWININICHANGE = 2
systemparametersinfo(SPI_SETDESKWALLPAPER,0, "c:\windows\CIRCLES.bmp" , SPIF_UPDATEINIFILE + SPIF_SENDWININICHANGE)
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error   C0082:reference argument must be a non-constant and non-readonly variable reference.
请教大神指教！！

[ 本帖最后由 mumu9341 于 2015-9-9 19:04 编辑 ]